1. Field of the Invention
The present invention is related to a process for preparing divinylarene dioxides, particularly divinylarene dioxides derived from divinylbenzene. More specifically, the present invention relates to a process for preparing a divinylarene dioxide including reacting (a) at least one divinylarene with (b) at least one oxidant in the presence of (c) at least one transition metal complex catalyst.
2. Description of Background and Related Art
Divinylarene dioxides, particularly divinylbenzene dioxide (DVBDO) and others which are derived from divinylbenzene (DVB) are a class, in general, of epoxy resins, in particularly diepoxides. These diepoxides can be used as either reactive diluents or as the main epoxy resin matrix in epoxy thermoset formulations. DVBDO itself has a very low liquid viscosity (for example, a liquid viscosity of less than about 0.02 Pa·s (20 centipoise) making DVBDO especially useful in the preparation of epoxy resin formulations requiring a low viscosity. Epoxy resin formulations made from DVBDO are useful as intermediates for preparing various other products. For example, epoxy resin formulations made from DVBDO are suitable for use in the fields of coatings, composites, and molding compositions.
Heretofore, previously known processes for the preparation of divinylarene dioxides have been unsuccessful in producing a high conversion and a high selectivity of DVBDO. The previously known processes for the preparation of DVBDO typically use hydrogen peroxide (H2O2) or peracetic acid as the oxidant reactant. For example, the process described in Inoue et. al., Bull. Chem. Soc. Jap., 1991, 64, 3442, employs H2O2. JP 09286750 discloses a process for producing DVBDO by the epoxidation of DVB using peracetic acid and H2O2. Another process for preparing DVBDO using peracetic acid is described in U.S. Pat. No. 2,982,752. The above known DVBDO epoxidation processes suffer from various problems including for example, the production of low yields and low selectivities of DVBDO.
Another problem with the processes of the prior art includes the production of undesirable by-products or the formation of side reactions. For example, Worzakowska M, J. Appl. Polym. Sci., 2007, 103, 462 discloses that DVBDO is prepared using a magnesium oxide catalyst in acetonitrile and H2O2, resulting in the formation of equivalent amount of acetamide by-product and a mixture of mono- and di-epoxides. Ruggli et al., Helvetica Chimica Acta, (1940), 23, 718 describes preparing DVBDO from benzene dialdehyde and diazomethane. Hopff et al., Helvetica Chimica Acta, (1957), 40, 274; and German Patent No. DE 1079614 describes a complicated three-step process for preparing DVBDO by reducing chloroacetylbenzene with lithium aluminum hydride, and subsequently removing HCl from chlorohydrins. Sulfonium ylides for preparing epoxides from carbonyl compounds are described in Corey et al., J. Am. Chem. Soc., 1962, 84 (5), pp. 867-868.
DVBDO is also prepared by treatment of p-terephthaldehyde with trimethylsulfonium chloride yielding p-DVBDO in 50% yield as described in U.S. Pat. No. 3,442,912 and European Patent No. 94726. U.S. Pat. No. 5,962,547 discloses the preparation of DVBDO using potassium persulfate in an acetone-water reaction mixture with no catalyst. No data on product purity or epoxide yield is disclosed in U.S. Pat. No. 5,962,547.
The above processes known in the prior art all suffer, for example, from the disadvantage of generating residual by-products from the oxidizing agent. The residual by-products, such as acids when peracids are the oxidants, or sulfides when sulphonium salts are oxidants, need to be separated from the desired DVBDO product. In addition, the different known preparations usually provide low yields of DVBDO; or if the yield of DVBDO is high, the process requires an inconveniently long reaction time to form the high yields of DVBDO. For example, the reaction time can be as much as 4 days. None of the previously known prior art processes for the preparation of DVBDO can successfully produce DVBDO in high yields (for example greater than 50%) efficiently and economically. In addition, the prior art processes do not produce DVBDO without co-producing undesirable by-products such as acetamide or acetic acid. The acid by-product is especially disadvantageous due to the acid sensitivity of DVBDO.
Accordingly, it is desired to develop a process for successfully preparing a divinylarene dioxide without co-producing undesirable by-products and while the process produces the divinylarene dioxide in high yields economically and efficiently.